A related-art piston cooling device in an internal combustion engine is configured such that a nozzle pipe communicating with an oil passage provided in the internal combustion engine is extended toward a back surface of a piston and oil is injected from the nozzle pipe.
For example, JP-A-2015-31246 discloses a cooling device which is detachably attached to an internal combustion engine. The cooling device includes a main body, a filter which is detachably provided at an upstream side of the main body in an oil flow path, and a nozzle pipe which is provided at a downstream side of the main body. The main body is attached to the internal combustion engine while the filter is mounted on the main body.
The piston cooling device disclosed in JP-A-2015-31246 has a structure in which the filter which is detachably provided at the upstream side of the main body in the oil flow path in a cap shape can prevent clogging of the nozzle pipe and trap foreign matters or foreign particles in the oil.
However, since the piston cooling device is provided in a crankcase of the internal combustion engine and its own size is small, it is difficult to increase a filter area and extending the life (maintenance cycle) of the filter.